tmux: ignore CVE-2020-27347

Details: https://nvd.nist.gov/vuln/detail/CVE-2020-27347

The fix for this vulnerability was backported to the recipe's version,
and it is included already.

Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>

meta-oe/recipes-extended/tmux/tmux_3.1c.bb

@@ -23,3 +23,7 @@ do_configure:prepend() {
     # not automatically created when building outside the source directory.
     mkdir -p ${B}/compat
 }
+
+# The fix was backported to the user version:
+# https://github.com/tmux/tmux/commit/d0ad34e94d63def5178f02281637d2d15cb42c88
+CVE_CHECK_IGNORE += "CVE-2020-27347"